This invention relates generally to the field of electronic film processing and more particularly to a system and method for digital color dye film processing.
Images are used to communicate information and ideas. Images, including print pictures, film negative, documents and the like are often digitized to produce a digital image that can then be instantly communicated, viewed, enhanced, modified, printed or stored. The increasing use and flexibility of digital images, as well as the ability to instantly communicate digital images, has led to a rising demand for improved systems and methods for film processing and the digitization of film based images into digital images. Film based images are traditionally digitized by electronically scanning a film negative or film positive that has been conventionally developed using a wet chemical developing process, as generally described below.
Undeveloped film generally includes a transparent base and one or more emulsion layers containing a dye coupler and a photosensitive material, such as silver halide, that is sensitive to electromagnetic radiation, i.e., light. In color films, independent emulsion layers are sensitized to different bands, or colors, of light. In general, one or more emulsion layers are sensitized to light associated with the colors of red, green and blue. When a picture is taken, the photosensitive material is exposed to light from a scene material to produce a chemical change in the photosensitive material. The greater the intensity of light interacting with the photosensitive material, the greater the chemical change in the photosensitive material. The photographic film can then be chemically processed to produce a fixed image of the scene based on this chemical change.
In a traditional wet chemical developing process, the film is immersed and agitated in a series of tanks containing different processing solutions. The first tank typically contains a developing solution. The developing solution chemically reacts with the exposed silver halide to produce elemental silver grains in each emulsion layer of the film. The metallic silver forms a silver image within each emulsion layer of the film. The by-product of the chemical reaction combines with the dye coupler in each emulsion layer to create a dye cloud around each developing silver halide grain. The color of the dye cloud is complementary to the band of light to which the emulsion layer has been sensitized. For example, the red sensitized layer typically produces a cyan dye image, the green sensitized layer a magenta dye image, and the blue sensitized layer a yellow dye image. The density of the silver image and the corresponding dye image in each emulsion layer are typically directly proportional to the logarithm of the intensity of light to which the film was exposed. The developing process is generally stopped by removing the film from the developer tank and rinsing the developing solution from the film with water or an acidic solution.
Conventional wet chemical developing processes remove both the silver image and the undeveloped silver halide grains from the film to produce a film negative having only a dye image within the film negative. To remove the silver image and undeveloped silver halide, the developed film is immersed and agitated in a tank of bleaching solution. The bleaching solution chemically oxidizes the metallic silver forming the silver image and converts the silver image into silver halide. The bleached film is then immersed and agitated in a tank of fixer solution. The fixer solution removes the silver halide from the film by substantially dissolving the silver halide crystals. The fixer solution is thereby contaminated with dissolved silver compounds and becomes a hazardous waste byproduct of the wet chemical developing process. The film is then washed, stabilized and dried to produce a conventional film negative. The film negative can then be used to produce a corresponding image on photographic paper by methods known to those skilled in the art.
Conventional film digitization processes scan the film negative using a conventional electronic scanner to produce a digital image that electronically represents the original scene. Conventional electronic film scanners generally operate by directing white light through the film negative. The light interacts with the dye clouds forming the image, i.e. the dye image, and the intensity of the red, green and blue light passing through the film are recorded by a sensor. The sensor data is used to produce the digital image.
A relatively new process under development is digital film processing (DFP). DFP systems directly scan the film during the development process. In particular, instead of scanning the dye image in the film, conventional DFP systems scan the silver image formed in the emulsion layers while the film is developing. In conventional DFP systems, the film is scanned using infrared light. Scanning with infrared light prevents the film from being fogged and allows the developing film to be scanned at different times during the development process in order to acquire image data at different exposure levels.
The DFP scanning process is generally accomplished by measuring infrared light reflected from the developed silver image in the front and back emulsion layers, and measuring the infrared light transmitted through the film. The reflected and transmitted light measurements of the film provide image data from the blue, red, and green sensitized emulsion layers, respectively. The measured reflected and transmitted light data is processed to produce the digital image.
One embodiment of the invention is a digital color dye film processing system for developing and scanning silver halide based film. In this embodiment, the digital color dye film processing system comprises an applicator station, a processing station, a scanning station, and a data processing system. The applicator station operates to coat a developer solution on the film. The development solution interacts with the exposed silver halide within the film to produce metallic silver grains. The processing station operates to coat at least one processing solution on the film. The processing solution substantially oxidizes the metallic silver grains and dissolves the silver halide. The scanning system operates to scan the film coated with the developer solution and the processing solution to produce sensor data. The data processing system operates to receive and process the sensor data to produce a digital image. In a particular embodiment, the scanning system scans the film with visible light and infrared light. The infrared light detects any occlusions within the film and the visible light detects the dye images as well as any occlusions within the film. The sensor data corresponding to the visible light and infrared light is processed by the data processing system to correct for the occlusions within the film.
Another embodiment of the invention is a system for processing silver halide based film. In this embodiment, the system comprises an applicator station, a development station, and a processing station. The applicator station operates to apply a developer solution onto the film. The development solution interacts with the silver halide in the film to produce metallic silver grains and at least one dye image within the film. The development station operates to substantially control the environment surrounding the film during development of the film. The processing station operates to apply at least one processing solution to the film, wherein the processing solution substantially oxidizes the metallic silver grains to produce silver halide and dissolve the silver halide. In a particular embodiment, the at least one processing solution comprises a blix processing solution. A blix solution is a processing solution, which includes the functionality of both a bleach and a fixer. In another embodiment, the at least one processing solution comprises a bleach processing solution and a fixer processing solution.
Another embodiment of the invention is a system for digitizing a developed film. The system comprises a lighting system and a sensor system. The lighting system operates to illuminate developed film coated with a developer solution and at least one processing solution. The sensor system operates to measure the illumination from the film and produce sensor data. In a particular embodiment, the illumination produced by the lighting system comprises visible and infrared light. In another embodiment, the sensor system includes a mirror for separating the visible light and the infrared light. In this embodiment, the mirror may comprise a hot mirror or a cold mirror.
A particular implementation of the invention is a method for digitizing film. In this implementation, the method comprises illuminating a film coated with a developer solution and at least one processing solution, and measuring the illumination from the film and producing sensor data. In a particular implementation, the method includes processing the sensor data to compensate for any occlusions within the film to produce a corrected digital image. The corrected digital image can be printed, stored, communicated over the Internet, displayed, and enhanced.
Another implementation of the invention is a method for developing and digitizing exposed film having multiple emulsion layers containing silver halide. In this implementation, the method comprises applying a developer solution to the film to produce metallic silver grains and a dye image within the film, then applying at least one processing solution to the film, wherein the processing solution operates to oxidize the metallic silver grains and dissolve the silver halide in the film. The coated film is then scanned with light and the resulting sensor data is processed to produce a digital image. In a particular implementation, the sensor data is processed to compensate for any occlusions within the film to produce digital image. In a specific implementation, the sensor data is processed by calculating a correction factor for each pixel based on an infrared record and applying the correction factor to the red, green, and blue records for each pixel to produce the digital image. In another implementation, the method includes drying the coated film prior to scanning the coated film.
Yet another embodiment of the invention is a coated film negative produced by a process that comprises applying a developer solution to a film having silver halide to produce metallic silver grains and a dye image within the film, applying at least one processing solution to the film, wherein the processing solution operates to oxidize the metallic silver grains and dissolve the silver halide in the film; and drying the developer solution and the processing solutions on the film to produce the coated film negative.
Yet another embodiment of the invention is a digital image produced by a process that includes illuminating a film coated with a developer solution and at least one processing solution, measuring the illumination from the film and producing sensor data that is processed to produce the digital image.
The invention has several important technical advantages. Various embodiments of the invention may have none, some, or all of these advantages. An advantage of at least one embodiment is that environmentally hazardous effluents are not created by the removal of silver from the film. In particular, no water plumbing is required to process the film in accordance with at least one embodiment of the invention. As a result, this embodiment is less expensive that conventional wet chemical processing systems and can be located at any location. In contrast, conventional wet chemical processing of film often requires water plumbing and removes the silver from the film, which produces environmentally hazardous effluents that are controlled by many government regulatory agencies.
Another advantage of at least one embodiment of the invention is that the invention can be embodied in a simple user operated film processing system, such as a self-service kiosk. In this embodiment, skilled technicians are not required, thereby reducing the cost associated developing and processing film. In addition, at least one embodiment of the invention allows the film to be developed and processed faster than conventional wet chemical processing of the film.
Yet another advantage of at least one embodiment is that optical occlusions scanned during the digitization process can be substantially removed from the digital image. Optical occlusions may be caused by residual silver within the film, opacity, particulate, or any other defect that blocks light transmitted through the film. As a result, the quality of the digital image can be improved.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.